In recent years, many touch panels that materialize an interactive input system have been used as one of man-machine interfaces. With regard to a position-sensing method, the touch panels include touch panels according to optical, ultrasonic, capacitance and resistant film systems, etc. Of these, the resistant film system is simple and excellent in the price/performance ratio and is hence rapidly spread in recent years.
A touch panel according to a resistant film system is an electronic part having a constitution in which two films or sheets having a transparent conductive layer each on facing sides are held at a constant distance from each other. A movable electrode substrate (electrode substrate on a viewing side) is pressed and dented with a pen or a finger to bring it into contact, and electrically connect it, with a fixed electrode substrate (electrode substrate on an opposed side), whereby a sensor circuit senses a position to input as predetermined. In this case, interference fringes called Newton rings can appear around a pressed portion. Further, even in a non-pressed state, Newton rings can sometimes appear where a distance between the movable electrode substrate and the fixed electrode substrate is decreased by the flexure of the movable electrode substrate. When Newton rings appear, the visibility of a display is degraded.
As a method for reducing Newton rings that appear between the two transparent electrode substrates constituting a touch panel according to a resistant film system, there is disclosed a method in which a coating layer containing a filler having an average primary particle diameter of 1 to 4 μm and a transparent conductive layer are formed on a plastic film (see Patent Document 1). Further, there is also disclosed a method in which a projected coating layer (layer having projections) containing silica particles having an average secondary particle diameter of 1.0 to 3.0 μm is formed on a plastic film (see Patent Document 2).
When a touch panel uses a transparent conductive laminate in which a coating layer containing particles having an average primary particle diameter or average secondary particle diameter of about several μm and a transparent conductive layer are formed on a plastic film, the development of Newton rings are reduced. When the above touch panel is set on a high-definition display in recent years, a resin around particles in the above coating layer performs a lens effect, whereby there is caused a problem that the separation (flicker) of a color from the display is caused and that the visibility of the display is badly degraded.
As other coating layer for reducing the Newton rings, there is a Newton-Rings-preventing layer (anti-Newton-rings layer) using a resin containing two or more matting agents having different average particle diameters and a binder (see Patent Document 3).
An anti-Newton-rings layer formed by the above method can prevent the flicker on a high-definition display. Both of particles having an average particle diameter of 1 to 15 μm and fine particles having an average particle diameter of 5 to 50 nm are added for the purpose of matting. Essentially, since fine particles having a size of 5 to 50 nm are much smaller than the wavelength of visible light, no haze occurs even when fine particles of this size are incorporated into a resin that constitutes a binder. However, when Examples and Comparative Examples described in Patent Document 3 are compared, the haze is increased by the addition of fine particles having a size of 5 to 50 nm, so that it is assumed that the fine particles form secondary aggregates. It is seen that the flicker is controlled by an increase in the haze, i.e., matting. An anti-Newton-rings layer formed by the above method has a problem that visibility of a display is degraded due to an increase in haze.
Patent Documents 1 to 3 disclose methods for forming an anti-Newton-rings layer for preventing Newton rings that appear due to a gap between the movable electrode substrate and fixed electrode substrate of a touch panel. However, the anti-Newton-rings layer formed by these methods contains inorganic or organic fine particles thereby to form concavoconvex shapes. Therefore, a surface on which the transparent conductive layer is formed has numerous projections of the inorganic or organic fine particles, and when a sliding durability or edge-writing durability test required of a touch panel is carried out, there is a problem that the transparent conductive layer starts to deteriorate or peel off at projection portions formed of the inorganic or organic fine particles, which finally leads to a decrease in the electric properties of a touch panel.
Further, when a push point durability test is carried out, the projections formed of the inorganic or organic fine particles contained in the anti-Newton-rings layer of the movable electrode substrate destroy dot spacers formed on the fixed electrode substrate to spread them inside a touch panel. Broken pieces of the thus-spread dot spacers hinder the electric connection between the movable electrode substrate and the fixed electrode substrate, and they adhere to and damage the transparent conductive layer, so that there is also a problem that the electric property of a touch panel is degraded.
Further, when an anti-Newton-rings layer formed by incorporating these inorganic or organic fine particles is used as a fixed electrode substrate, projections formed of the inorganic or organic fine particles adhere to and damage the transparent conductive layer of the movable electrode substrate, which leads again to a problem that the electric property of a touch panel is degraded.
Meanwhile Patent Document 4 discloses an antiglare film material containing no fine particles, while it discloses nothing concerning the application thereof to a transparent conductive laminate.    (Patent Document 1) JP 10-323931 A    (Patent Document 2) JP 2002-373056 A    (Patent Document 3) JP 2001-84839 A    (Patent Document 4) WO2005/073763